Throughout his career, Hopper was fascinated by dramatic lighting and nowhere is this more evident than in his nighttime pictures, where brightly lit interiors contrast with the darkness outside. Glowing fluorescent or electrical lights, which illuminate windows and spill onto otherwise darkened street, set the tone for many of Hopper's paintings and imbue the works with an air of mystery. The voyeuristic possibilities inherent in the modern city, where people lived in close proximity but often with anonymity—are especially apparent at night. Hopper frequently depicted stolen glances from fast-moving elevated trains and glimpses from windows into neighboring buildings, where figures are busy with their own private concerns, unaware or unconcerned that they are being watched.